Scheme/Lisp compilers already allocate variables on the stack when it's safe to do so. It isn't always safe to do so. The part about "lambda-blocks w/o heap a

Scheme/Lisp compilers already allocate variables on the stack when it's safe to do so. It isn't always safe to do so. The part about "lambda-blocks w/o heap allocation" describes a missing feature, not an innovation in concurrency or efficiency.